Safety-brake pawl.



PATENTED OCT. 24, 1905.

A. X. KENNEDY.

SAFETY BRAKE PAWL.

APFLIGATION FILED 31111.16, 1905.

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ALEXANDER X. KENNEDY, OF TYRONE, PENNSYLVANIA, ASSIGNOR OF ONE-HALF TOTHOMAS E. MOLAUGHLIN, OF SNOWSHOE, PENNSYL- VAN IA.

SAFETYBRAKE FAWL.

Specification of Letters Patent.

Patented Oct. 24, 1905.

Application filed January 16, 1905. Serial No. 241,319.

To all whom/ it TH/(I/Z/ concern.-

Be it known that I, ALEXANDER X. KEN- NEDY, a citizen of the UnitedStates, residing at Tyrone, in the county of Blair and State ofPennsylvania, have invented new and useful Improvements in Safety-BrakePawls, of which the following is a specification.

This invention relates to a safety-brake pawl for use in connection withratchet-wheels of brake-shafts to secure said shafts against retrograderotation when the brakes are applied. the object of the invention beingto pro vide a pawl appliance which is simple and inexpensive ofconstruction, capable of being used in place of the ordinary brake-pawland in connection with the usual type of ratchetwheel, which may beconveniently retracted when positively operated to release thebrakeshaft, but cannot become displaced by ordinary shocks or jars, andwhich will be efiectually protected from snow and ice and prevented frombecoming inoperative thereby or affected by other climatic changes orconditions.

With this and other objects in view the invention consists of thefeatures of construction, combination, and arrangement of partshereinafter fully described, reference being had to the accompanyingdrawings, in which Figure'l is a top plan View of a brake-pawl embodyingmy invention, showing the same in engagement with the ordinary type ofratchet-wheel. Fig. 2 is a side elevation of the same, and Fig. 3 is ahorizontal section through the pawl and its supporting block or castingand the end wall of the cover-plate coo perating with said block orcasting to form the pawl-casing.

Referring now more particularly to the drawings, the numeral 1represents a suitable support, which may be a portion of the wall orplatform of a car or a bracket connected thereto and through whichextends the brakeshaft 2, to which is fixed the usual ratchetwheel 8.

The pawl mechanism comprises a block or casting 4, provided at one endwith a rightangularly-extending arm 5, which is bifurcated at its freeend to form a receiving-slot 6, the inner wall of the block or castingbeing extended from the other end of said block on a gradual curve, asindicated at 7, to thicken or strengthen the block at its point ofjunction with the arm 5. The upper surface of the arm 5 projects abovethe upper face of the block 4: and is provided with a plane-surfacedinner edge forming an abutting shoulder 8. The block 4 is designed torest with its lower surface against the support 1 and is of sufficientdepth or thickness to provide for the formation of the slot 6 ofsufficient depth to receive a pawl of requisite width and thickness andto form withacoverplate 8 a casing to protect the body portion of thepawl and its actuating-spring. The plate 8 is approximately rectangularin form and rests against the upper surface of the block or casting land against the shoulder 8 and is provided at its end opposite saidshoulder 8 with a downwardly-projecting flange 9, which extends downward into contact with the support 1, the block 4, with its arm 5, thusforming the rear Wall and one of the side walls, the plate 8 the topwall, and the flange 9 the other side wall of a casing which is open atits forward end or at the end opposite the said block 4.

The pawl 10 is properly curved to engage the teeth of the ratchet-wheel13 and is pro vided with an enlarged central portion 11, which fits andturns within the slot 6, and has an arm 12, which is free to swing inthe open side of the casing and is formed at its free end with anoutwardly-projecting lug or enlargement 13, which normally extendsbeyond the casing to provide an operating portion which may be pressedupon by the hand or foot of the operator to force the arm 12 inward, andthereby swing the pawl 10 out of engagement with the ratchet-wheel.Bolts 14 pass through the rear portion of the coverplate 8 and block 4and also through the supporting portion 1 and connect the casing to thelatter, and another bolt 1a passes through the bifurcated end of the arm5 and forms a pivot on which the intermediate portion 11 is fitted topivot the pawl to swing. A coiled spring 15 is disposed within thecasing and has one end suitably secured to the inner face of the block 4and its outer end connected to the free end of the arm 12 of the pawl.This spring by expansion forces the arm 12 outward, thus projecting andmaintaining the pawl 10 in engagement with the teeth of theratchet-wheel 3, while permitting said pawl to vibrate and run over thecurved surfaces of said teeth when the brake-rod is being turned toapply the brakes. When the motion of the brake-rod is arrested, however,retrograde movement of the ratchet-wheel is prevented by the engagementof the pawl with the straight shoulder of the coacting ratchettooth,with which it is securely held in engagement by the action of the spring15, Whose pressure is sufiicient to prevent the pawl from moving out ofengagement with said tooth unless pressure is applied directly to theprojecting portion 13 of the pawl-arm 12. It will thus be seen that thepawl cannot be caused to jump out of engagement by any ordinary shock orstrain, and thus will securely hold the rod or shaft 2 against rotation.

As the cover-plate, with its flange 9, forms with the block a housingwhich is open only at its forward side for the projection of the portion13, the pawl is protected and prevented from becoming choked by ice orsnow or other deleterious climatic influences and accordingly willalways be in condition for operation.

From the foregoing description, taken in connection with theaccompanying drawings, the construction and mode of operation of thepawl will be readily understood, and it will be seen that a constructionis provided which is exceedingly simple and compact and which insuresperfect engagement of the pawl with the ratchet-wheel at alltimes. Thepawl may be readily substituted for the ordinary pawl and used inconnection with existing brake mechanism without any changes in theconstruction thereof.

Changes in the form, proportions, and minor details of construction maybe made within the scope of the invention without departing from thespirit or sacrificing any of the advantages thereof.

Having thus fully described the invention, what is claimed as new isv 1. In a brake mechanism, the combination with a brake-shaft providedwith a ratchetgear, of a casing having an open side arranged obliquelyto the gear, a pawl pivoted between its ends at a corner portion of thecasing and provided with oppositely-disposed arms, one of said armshaving an engaging end to cooperate with the ratchet-gear and the othera laterally-projecting finger-piece, the arms of the pawl being disposedin substantial alinement so that the finger-piece will project throughthe obliquely-arranged open;

side of the casing when the pawl is in engagement with theratchet-wheel.

2. A pawl comprising ablock having a rightangular arm formed with abifurcated extremity, said arm being formed with a shoulder. acover-plate resting on the block and engaging said shoulder, a pawlpivoted in said bifurcated portion and provided with an engaging arm'anda retracting arm, the latter extending into the casing, and apressure-spring interposed between the block and retracting arm andacting on said arm to project the engaging arm, substantially asdescribed.

3. In a brake mechanism, the combination with a brake-shaft carrying aratchetwheel, of a pivoted pawl having arms arranged substantially inlongitudinal alinement, one of said arms having an acting end to engagethe ratchet-wheel, the other arm being provided with alaterally-projecting finger-piece, and a casing inclosing thelatter-named arm of the pawl and having an open side disposed obliquelyto the direction of extension of the pawl to normally expose thefinger-piece.

4. In a brake mechanism, the combination with a brake-shaft carrying aratchet-wheel, of a block having arms disposed at right angles to eachother, a cover-plate coacting with said arms to form a casing, a pawlpivoted to one of the arms and provided with an engaging arm and aretracting arm, the latter being formed with a finger-piece normallyprojecting from the casing, and a spring interposed between the otherarm of the block and the retracting arm of the pawl and acting on saidarm to project the engaging arm.

I In testimony whereof I affix my signature in presence of twowitnesses.

ALEXANDER X. KENNEDY.

Witnesses:

W. (J. VAN ScoYoc, F. L. STRUBLE.

